A. SELECT ename,sal*12 ‘Annual Salary’ FROM emp; 

B. SELECT ename,sal*12 “Annual Salary” FROM emp;

C. SELECT ename,sal*12 AS Annual Salary FROM emp;

D. SELECT ename,sal*12 AS INITCAP(“Annual Salary”) FROM emp;

如题正确答案是b选项

为什么不选c？
因为 “Annual Salary” 中间有空格